import pandas
data = pandas.read_csv('hongkong_children_height_weight.csv', index_col='Index')
data_sample_200 = data.sample(n=200, replace=False)
mu1 = data_sample_200['Height(inches)'].mean()
mu2 = data_sample_200['Weight(pounds)'].mean()

# 在默认情况下，pandas计算的标准差为样本标准差。
sigma1 = data_sample_200['Height(inches)'].var()*199/200
sigma2 = data_sample_200['Weight(pounds)'].var()*199/200

print(mu1, mu2, sigma1, sigma2)
print(data_sample_200.corr())